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| United States Patent |
5,254,443
|
|
Kok
, et al.
|
October 19, 1993
|
Photographic direct positive material containing a masked benzotriazole
stabilizer
Abstract
A photographic direct positive material is disclosed comprising a support
and one or more radiation sensitive emulsion layers containing internal
latent image-forming silver halide grains characterized in that at least
one of said emulsion layers further contains a masked stabilizer
corresponding to general formula (I):
##STR1##
wherein Z represents a lower alkyl group, a nitro group or a halogen atom,
n=0 to 4, and M represents a positive counterion.
Preferred compounds are 1-(2-sulphonatobenzoyl)-5-methyl-benzotriazole,
1-(2-sulphonatobenzoyl)-6-methyl-benzotriazole or a mixture of both.
The masked stabilizer is preferably incorporated in the emulsion layer(s).
The material preferably further contains a nucleating agent. Improved
direct positive sensitometric properties and wider exposure latitude
before encountering rereversal are obtained.
| Inventors:
|
Kok; Piet (Gent, BE);
Dewanckele; Jean-Marie O. (Drongen, BE)
|
| Assignee:
|
Agfa-Gevaert, N.V. (Mortsel, BE)
|
| Appl. No.:
|
915673 |
| Filed:
|
July 21, 1992 |
Foreign Application Priority Data
| Aug 13, 1991[EP] | 91202073 |
| Dec 16, 1991[EP] | 91203295 |
| Current U.S. Class: |
430/401; 430/487; 430/567; 430/598; 430/600; 430/614 |
| Intern'l Class: |
G03C 005/29; G03C 001/34 |
| Field of Search: |
430/567,598,600,614,401,487
|
References Cited
U.S. Patent Documents
| 4572892 | Feb., 1986 | Hoyen | 430/598.
|
| Foreign Patent Documents |
| 765944 | Oct., 1971 | BE | 430/614.
|
Primary Examiner: Baxter; Janet C.
Attorney, Agent or Firm: Breiner & Breiner
Claims
We claim:
1. Photographic direct positive material comprising a support and one or
more radiation sensitive emulsion layers containing internal latent
image-forming silver halide grains characterized in that at least one of
said emulsion layers further contains a compound corresponding to general
formula (I):
##STR10##
wherein Z represents a lower alkyl group, a nitro group or a halogen atom,
n=0 to 4, and M represents a positive counterion.
2. Photographic direct positive material according to claim 1 wherein said
material further contains a nucleating agent.
3. Photographic direct positive material according to claim 2 wherein said
nucleating agent is an aryl hydrazide derivative.
4. Photographic direct positive material according to claim 2 wherein said
nucleating agent is a N-substituted cycloammonium quaternary salt.
5. Photographic direct positive material according to claim 1 wherein said
internal latent image forming silver halide grains are core-shell grains.
6. Photographic direct positive material according to claim 5 wherein the
core of said core-shell grains is chemically ripened.
7. Photographic direct positive material according to any of claims 1 to 6
wherein said internal latent image-forming silver halide grains are
internally doped with a polyvalent metal dopant.
8. Photographic direct positive material according to claim 7 wherein said
polyvalent metal dopant is chosen from group VIII of the Periodic Table.
9. Photographic direct positive material according to claim 1 wherein said
compound according to general formula (I) is present in a concentration
comprised between 10.sup.-4 and 5.times.10.sup.-2 mole per mole silver
halide.
10. Photographic direct positive material according to claim 1 wherein said
compound according to general formula (1) is
1-(2-sulphonatobenzoyl)-5-methyl-benzotriazole or
1-(2-sulphonatobenzoyl)-6-methyl-benzotriazole or a mixture of both.
11. Photographic direct positive material according to claim 1 which
contains no intermediate non-light sensitive layer between the support and
the emulsion layer(s).
12. A method for forming an image comprising imagewise exposing a
photographic direct positive material according to claim 1, and developing
said material (a) in the presence of a nucleating agent, or (b) with light
flashing of said material during processing.
Description
DESCRIPTION
1. Field of the Invention
The present invention relates to direct positive black-and-white
photographic materials. More particularly it relates to direct positive
materials containing masked stabilizers of a particular type.
2. Background of the Invention
Photographic black-and white materials producing a density upon development
which is directly related to the radiation received on exposure are termed
negative working. From such a negative image a positive image resembling
the original recorded scene can be produced by copying it on another
negative working material. Direct positive images are understood in
photography to be formed without intervention of a negative image by
development of photographic emulsion layers containing specially designed
so-called direct positive emulsions.
In this method of photographic imaging the application of two main types of
emulsions can be distinguished, the first one being externally fogged
emulsions, usually containing an electron acceptor, the second one being
unfogged internal latent image-forming emulsions, which are
positive-working by fogging development, preferably in the presence of a
so-called nucleating agent.
Surface-fogged emulsions are disclosed e.g. in Kendall U.S. Pat. No.
2,541,472, Schouwenaars GB 723,019, Illingsworth U.S. Pat. No. 3,501,307,
Berriman U.S. Pat. No. 3,367,778 and Research Disclosure, Vol 134, Jun.
1975, Item 13452.
Internal latent image-forming silver halide grains are disclosed in e.g.
Ives U.S. Pat. No. 2,563,785, Evans U.S. Pat. No. 3,761,276, Knott U.S.
Pat. No.2,456,953 and Jouy U.S. Pat. No. 3,511,662. Further patents
include Davey U.S. Pat. No. 2,592,250, which describes internal sensitive
emulsions prepared by conversion, Porter U.S. Pat. No. 3.206,313, which
discloses direct positive emulsions of a particular core-shell type,
Milton U.S. Pat. No. 3,761,266, illustrating chloride rich direct positive
emulsions, Gilman U.S. Pat. No. 3,761,267, Atwell U.S. Pat. No. 4,035,185,
and Daubendiek U.S. Pat. No. 4,504,570, which discloses direct positive
emulsions of the internal latent image-forming type containing tabular
grains.
In conventional silver halide photography, both negative or direct positive
working, so-called stabilizers or anti-foggants are well known ingredients
which can be incorporated in photographic materials and/or in photographic
developing solutions. Their principal function consists in minimizing the
obtained fog level on developing exposed photographic materials and/or to
reduce the rise of development fog after prolonged storage of the
photographic material compared to the fog level of a freshly coated
material. Numerous chemical classes of stabilizers are disclosed in
photographic scientific and patent literature. Suitable examples are e.g.
the heterocyclic nitrogen-containing compounds such as benzothiazolium
salts, imidazoles, nitroimidazoles, benzimidazoles, nitrobenzimidazoles,
chlorobenzimidazoles, bromobenzimidazoles, indazoles, nitroindazoles,
mercaptothiazoles, mercaptobenzothiazoles, mercaptobenzimidazoles,
mercaptothiadiazoles, aminotriazoles, benzotriazoles (preferably
5-methyl-benzotriazole), nitrobenzotriazoles, mercaptotetrazoles, in
particular, 1-phenyl -5-mercapto-tetrazole, mercaptopyrimidines,
mercaptotriazines, benzothiazoline-2-thione, oxazoline-thione,
triazaindenes, tetrazaindenes and pentazaindenes, especially those
described by Birr in Z. Wiss. Phot. 47 (1952), pages 2-58,
triazolopyrimidines such as those described in GB 1,203,757, GB 1,209,146,
JA-Appl. 75-39537, and GB 1,500,278, and
7-hydroxy-s-triazolo-[1,5-a]-pyrimidines as described in U.S. Pat. No.
4,727,017, and other compounds such as benzenethiosulphonic acid,
toluenethiosulphonic acid, benzenethiosulphinic acid and
benzenethiosulphonic acid amide. A review of useful compounds is published
in Research Disclosure No 17643 (1978). Chapter VI.
As is well known in the art direct positive silver halide emulsions exhibit
various disadvantages as compared to negative working emulsions. The high
level of sensitivity which can be routinely attained with negative
emulsions cannot easily be reached with direct positive emulsions. It is
not easy to reconciliate the various demands of high maximum density, good
contrast, low minimum density and sufficient speed. More particularly
direct positive emulsions of the internal sensitivity type can suffer from
a second disadvantage known as rereversal on overexposure. This means
that, with increasing overexposure starting from an exposure level beyond
the toe of the direct positive sensitometric curve, a negative gradient
starts to build up. As a practical result the high-lights of an original
scene which contains a broad range of reflected light intensities tend to
be reproduced as highly disturbing negative images.
Several patent publications disclose particularly usefull classes of
antifoggants or stabilizers in connection with direct positive materials
in order to counteract their specific disadvantages. So Unexamined
Japanese Patent Publication (Kokai ) 62-229134 describes benzotriazoles in
backing layers of materials containing core-shell type direct positive
emulsions in order to improve processing stability. The addition of
several kinds of mercapto-substituted N-containing heterocyclic compounds
to direct positive emulsions of the internal sensitivity type are
disclosed in Unexamined Japanese Patent Publications (Kokai) 63-029752,
01-197742, 63-040148 and 63-040148. In Kokai 57-096331 the addition after
physical maturation to direct positive emulsions of specific
mercaptotriazoles in order to improve raw stock stability is described.
Stauffer U.S. Pat. No. 2,497,917 recognized that certain antifoggants when
used in internal latent image-forming direct positive elements not only
reduce the minimum density but also increase maximum density. Members of
this special class of antifoggants are known to be effective whether
incorporated in the photographic element itself or in a developing
solution. Further applications of maximum density enhancing antifoggants
are illustrated in Evans U.S. Pat. No. 3.761,276 cited above. Hoyen U.S.
Pat. No. 4,572,892 discloses a black-and-white direct positive
photographic element comprising one or more emulsion layers containing
internal latent image-forming silver halide grains and further a maximum
density enhancing 1,2,3-triazole antifoggant (preferably a benzotriazole
derivative) which has to be incorporated in an undercoat layer between the
emulsion layer(s): in the preferred embodiment a nucleating agent is
present, e.g. an arylhydrazide derivative. An improved direct positive
sensitometry is claimed together with an extended overexposure margin
before rereversal occurs. However the practice of this procedure exhibits
the technological and economical disadvantage of the requirement for an
extra undercoat layer. Further the solubility in water of benzotriazole
derivatives is rather limited so that for the incorporation of higher
amounts the use of organic solvents which are ecologically disadventageous
are needed.
The present invention relates to a further improvement to the teachings of
U.S. Pat. No. 4,572,892.
It is an object of the present invention to provide a photographic direct
positive material, working by means of internal image-forming silver
halide emulsion grains, with excellent sensitometric characteristics,
being high maximum density, low minimum density, good contrast and
sensitivity.
It is a further object of the present invention to provide a direct
positive material with sufficient overexposure latitude before
encountering rereversal.
It is still a further object of the present invention to realize the
benefits of such direct positive material without requirement for an
intermediate layer between support and emulsion layer(s), also called
undercoat layer. 3. Summary of the Invention
The objects of the present invention are realized by providing a
photographic direct positive material comprising a support and one or more
radiation sensitive emulsion layers containing internal latent image
forming silver halide grains characterized in that at least one of said
emulsion layers further contains a compound corresponding to general
formula (I):
##STR2##
wherein Z represents a lower alkyl group, a nitro group or a halogen atom,
n=0 to 4, and M represents a positive counterion.
According to a further aspect of this invention the described direct
positive material is meant to be processed in a surface developer (a) in
the presence of a nucleating agent or (b) with light flashing of the
photographic element. However procedure (a) constitutes the preferred
embodiment. Most preferably an arylhydrazide nucleating agent is used
which is preferably incorporated in an emulsion layer too.
4. DETAILED DESCRIPTION OF THE INVENTION
The 1-(2-sulphonatobenzoyl)-benzotriazole derivatives represented by
formula (I) and used in accordance with the present invention form a
subclass of a class of so-called masked stabilizers which was disclosed
for the first time in European Patent Application, filed 13.08.91 under
applic. No. 91202073.2. The term "masked stabilizer" refers to the fact
that these compounds are easily decomposed (or "demasked") to form the
free stabilizer molecule under the alkaline pH conditions commonly
occuring during the development step.
Thus, pages 12 and 13 of the European Patent Application Ser. No.
91202073.2 filed Aug. 13, 1991 disclose the following:
1.a. Preparation of 1-(2-sulphonatobenzoyl)-5-nitroindazole trimethylamine
salt
To a suspension of 179.5 g (1.1 mole) of 5-nitroindazole and 184 g (1 mole)
of o-sulphobenzoic acid anhydride in 2000 ml of dry acetone were added
dropwise while stirring 153 ml (1.1 mole) of triethylamine at reflux
temperature. Then the suspension was refluxed for another 6 hours. The
precipitate was filtered off at room temperature, washed with acetone and
dried. Yield: 323 g (72%); melting point: 210.degree. C.; chemical
structure confirmed by NMR analysis.
1.b. Preparation of 1-(2-sulphonatobenzoyl)-5-nitroindazole potassium salt
To a suspension of 268.8 g (0.6 mole) of
1-(2-sulphonatobenzoyl)-5-nitroindazole trimethylamine salt in 540 ml of
methanol and 360 ml of water was added at room temperature while stirring
a saturated potassium chloride solution containing 134 g (1.8 mole) of
potassium chloride in 400 ml of water. Then the suspension was stirred for
another two hours. After waiting for 12 hours the precipitate was filtered
off, washed with 480 ml of a water/methanol (1/1) mixture and finally
dried. Yield: 217 g (94%); melting point>300.degree. C.
1.c. Preparation of 1-(2-sulphonatobenzoyl)-benzotriazole triethylamine
salt
This compound was prepared in a similar way as explained in example 1.a.
with the exception that 1.1 mole of benzotriazole was used instead of
5-nitroindazole. Yield: 56%; melting point 180.degree. C.
1.d. Preparation of 1-(2-sulphonatobenzoyl)-5-methylbenzotriazole
triethylamine salt
This compound was prepared in a similar way as explained in example 1.a.
with the exception that 1.1 mole of 5-methyl-benzotriazole was used
instead of 5-nitroindazole. A mixture of the two positional isomers was
obtained. Yield: 46%; melting point: about 167.degree. C.
Examples of useful masked stabilizers (MS) according to formula (I) are set
forth in Table 1:
TABLE 1
______________________________________
MS-1 1-(2-sulphonatobenzoyl)-benzotriazole
MS-2 1-(2-sulphonatobenzoyl)-5-methylbenzotriazole
MS-3 1-(2-sulphonatobenzoyl)-6-methylbenzotriazole
MS-4 1-(2-sulphonatobenzoyl)-5-ethylbenzotriazole
MS-5 1-(2-sulphonatobenzoyl)-5-bromobenzotriazole
MS-6 1-(2-sulphonatobenzoyl)-5-chlorobenzotriazole
MS-7 1-(2-sulphonatobenzoyl)-4-nitro-6-chlorobenzotriazole
MS-8 1-(2-sulphonatobenzoyl)-5,6-dichlorobenzotriazole
______________________________________
The best results are obtained with compound MS-2 and with compound MS3, as
will become clear from the examples later on. During the acylation
reaction starting from free 5-methylbenzotriazole a mixture of the two
positional isomers 1-(2-sulphonatobenzoyl)-5-methylbenzotriazole (MS-2)
and 1-(2-sulphonatobenzoyl)-6-methylbenzotriazole (MS-3) are formed. On
demasking they both form the same methylbenzotriazole again. So the
isomers MS-2 and MS-3 can be used as a mixture.
It is specifically contemplated that in the practice of this invention the
masked stabilizer can be incorporated in the emulsion layer (or one of the
emulsion layers) itself and that there is no need for an extra undercoat
layer as opposed to the teaching of U.S. Pat. No. 4,572,892, cited above.
We think this is due to the special masked character of the compounds used
in accordance with the present invention. If one would incorporate,
contrary to the teachings of U.S. Pat. NO. 4,572,892, a free benzotriazole
stabilizer into the emulsion layer(s), this compound would be prematurely
adsorbed to the silver halide grain surface; as a consequence the
nucleation phase would be hampered and the development rate slowed down
resulting in a low direct positive maximum density. This problem can be
overcome, according to U.S. Pat. No. 4,572,892, by applying the free
stabilizer in an extra undercoat, from which it takes some time to diffuse
to the emulsion layer, or alternatively by incorporating the stabilizer in
a masked form in the emulsion layer as proposed in this invention.
Thanks to their higher solubily as compared to the corresponding free
stabilizers the masked benzotriazoles can simply be added as aqueous
solutions to the coating solution. The concentration of the masked
benzotriazoles in the emulsion layer is preferably comprised between
10.sup.-4 and 5.times.10.sup.-2 mole per mole of silver halide.
Preferred latent image-forming silver halide emulsions are so-called
core-shell emulsions consisting of a core and at least one shell with the
same or different halide compositions. Both shell and core can mutually
independently be composed of silver bromide, silver chloride, silver
chlorobromide, silver chloroiodide, silver bromoiodide and silver
chlorobromoiodide. The emulsions can show a coarse, medium or fine average
grain size and be bounded by (100), (111), (110) crystal planes or
combinations thereof. Also high aspect ratio tabular core-shell emulsion
grains can be contemplated as disclosed in U.S. Pat. No. 4,504,570. The
core-shell emulsions contain internal sensitization sites which can be of
various nature and which form an internal latent image upon exposure.
A first type of core-shell emulsions contains internal physical
sensitization sites formed by crystallographic irregularities in the phase
bounderies between a core and a shell of distinctly different halide
composition, e.g. a silver bromide core and a silver bromoiodide shell
with a relative high iodide percentage.
Another simple method for applying internal sensitization sites consists of
incorporating a polyvalent metal ion dopant in the core grains during
their formation. This metal dopant can be placed in the reaction vessel
prior to precipitation or it can be added to one or more of the solutions
taking part in the precipitation. Preferred polyvalent metal dopants are
elements of group VIII of the Periodic System, e.g. Iridium, as disclosed
in U.S. Pat. No. 3,367,778, or Rhodium. They are preferably used in the
form of a soluble salt or coordination complex. The usual concentration
range is comprised between 10.sup.-8 and 10.sup.-4 mole per mole of silver
halide.
The most common method of creating internal sensitization sites consists of
interrupting the precipitation after completion of the core and apply
chemical sensitization or even fogging to this core, after which process
the precipitation of the shell is resumed. The usual chemical ripening
agents containing middle-chalcogen elements like sulphur, selenium and
tellurium can be used as was disclosed e.g. in U.S. Pat. No. 3,761,276.
Preferably they are combined with compounds containing noble metal atoms,
e.g. gold. Contrast can be controlled by optimizing the ratio of
middle-chalcogen amount to gold sensitizer amount as is described in U.S.
Pat. No. 4,035,185.
The choice of the halide composition of the shell portion will depend on
the requirements of the specific photographic application. In order to
achieve fast developability emulsion shells with a high chloride content
are best suited. On the contrary when high sensitivity is most important
bromide or iodobromide grain shells are to be preferred. The shell portion
of the grain must contain a sufficient percentage of the total silver
halide in order to restrict access of a surface developer to the internal
sensitization centers. The surface of the finished core-shell emulsion
grains can be chemically sensitized or not. For obtaining good reveral
speed and maximum density a moderate degree of surface sensitization using
conventional techniques can be applied. This degree of chemical
sensitization is limited to that which will realize an optimal balance
between internal and surface sensitivity, the internal sensitization
usually remaining predominant.
It is specifically contemplated that in order to control sensitometric
characteristics two or more internal latent image-forming emulsions can be
blended before coating and thus be applied in the same emulsion layer.
Alternatively several different emulsions can be used each in a different
emulsion layer arranged in a pack. However in a most preferred embodiment
of the present invention simply one emulsion layer is coated containing
one direct positive emulsion or a blend of several direct positive
emulsions.
The internal latent image-forming emulsions can, if desired, be spectrally
sensitized according to the exposure source to be used depending on the
specific photographic application. Dyes that can be used for the purpose
of spectral sensitization include cyanine dyes, merocyanine dyes, complex
cyanine dyes, complex merocyanine dyes, hemicyanine dyes, styryl dyes and
hemioxonol dyes. Particularly valuable dyes are those belonging to the
cyanine dyes, merocyanine dyes and complex merocyanine dyes as described
by F. M. Hamer in "The Cyanine Dyes and Related Compounds", 1964, John
Wiley & Sons. The process of spectral sensitization can take place at any
stage of the emulsion preparation but most commonly spectral sensitization
is undertaken subsequent to the completion of surface chemical
sensitization, if any.
A preferred orthochromatic spectral sensitizing dye (SD-1) is represented
by following chemical formula:
##STR3##
In order to promote the formation of a direct positive image the
photographic materials of the present invention can be image-wise exposed
and then subjected to uniform flash lighting during processing. Preferably
however the direct positive image is formed with the aid of a so-called
nucleating agent (or development nucleator) which triggers development.
This nucleating agent can be present in the developing solution but most
preferably it is present in the photographic material itself. Since in the
preferred embodiment of this invention there is no undercoat non-light
sensitive layer the nucleating agent is preferably incorporated in the
emulsion layer(s). When used in the silver halide emulsion layer(s) the
development nucleators are present in a concentration of preferably
10.sup.-5 mole to 10.sup.-1 mol per mole of silver halide.
A first class of suitable development nucleators for use in accordance with
the present invention are the hydrazide-type compounds corresponding to
the following general formula N-1:
R.sup.1 --NH--NH--CO--R.sup.2 (N-1)
wherein each of R.sup.1 and R.sup.2 independently represent hydrogen, an
alkyl group, a substituted alkyl group, an aryl group, or a substituted
aryl group.
Preferred development nucleators for use in accordance with the present
invention are aryl hydrazides e.g. 1-formyl-2-phenyl-hydrazide,
1-p-acetamidophenyl -2-acetyl -hydrazide, and
1-[2-(2,4-di-tert-pentyl-phenoxy)-propionamidophenyll-2-formyl-hydrazide.
Another class of suitable hydrazide-type development nucleators are
hydrazides comprising a heterocyclic nitrogen-containing nucleus or a
substituted heterocyclic nitrogen-containing nucleus e.g. a thiohydantoin
nucleus and a mercaptotetrazolyl nucleus. Examples of such compounds are
the following compounds N-2 and N-3:
##STR4##
A preferred class of hydrazide-type development nucleators for use in
accordance with the present invention, which comprise a heterocyclic
nitrogen-containing nucleus are the hydrazines carrying a
pyrazolidin-3-one-1-yl-phenyl group or a substituted
pyrazolidin-3-one-1-yl-phenyl group. Examples of such preferred
development nucleators are the compounds according to the following
structural formulae N-4 and N-5:
##STR5##
An interesting class of development nucleators corresponding to general
formula N-1 are the aryl hydrazides containing water-solubilizing
polyhydroxy moieties. Representatives of this class correspond to the
following general formula N-6:
##STR6##
wherein n is a positive integer ranging from 1 to 10 and
R.sup.3 is hydrogen, an alkyl group, a substituted alkyl group, an aryl
group, a substituted aryl group, a heterocyclic group, or a substituted
heterocyclic group.
A suitable example of a heterocyclic group represented by R.sup.3 in
general formula N-6 is a pyrazolidin-3-one-1-yl group, which may be
substituted.
Examples of development nucleators corresponding to general formula N-6 are
the compounds, in which n is 4 or 5 and R.sup.3 stands for hydrogen.
Another preferred class of aromatic hydrazide nucleating agents are those
in which the aromatic nucleus is substituted with one or more groups to
restrict mobility and, preferably promote adsorption of the hydrazide
derivative to the silver halide grain surface. Preferred hydrazides of
this kind are represented by following general formula (N-7)
##STR7##
wherein Ac is an acyl group,
J.sup.1 is hydrogen and J.sup.2 is a sulphinic acid radical or vice versa,
Ph is a phenylene or substituted phenylene group, and
B is a moiety capable of restricting mobility, such as a ballasting or an
adsorption promoting moiety.
Hydrazides of this type are disclosed by Hess U.S. Pat. No. 4,478,928. A
preferred type of sulphinic acid radical is represented by the following:
##STR8##
wherein Ar is an aryl group or substituted aryl group, preferably phenyl
or naphthyl. A still further preferred class of aromatic hydrazide
nucleating agents are acylhydrazinophenylthioureas as disclosed by Leone
U.S. Pat. No. 4,030,925 and U.S. Pat. No. 4,276,364. other variants are
described by von Konig U.S. Pat. No. 4,139,387 and Adachi GB 2,012,443.
Still another preferred class of nucleating agents of the hydrazide type
consists of N-(acylhydrazinophenyl)thioamide compounds as disclosed in
Leone U.S. Pat. No. 4,080,207. Further preferred compounds are
triazolo-substituted phenyl hydrazide nucleating agents as described by
Sidhu U.S. Pat. No. 4,278,748. Comparable nucleating agents having a
somewhat broader range of adsorption promoting groups are disclosed in GB
2,011,391.
Other useful hydrazine and hydrazide nucleating agents have been disclosed
in e.g. Research Disclosure Item 23510 Vol. 235, Nov. 10, 1983 and in U.S.
Pat. No. 4,269,929, US 4,243,739, U.S. Pat. No. 4,272,614. Recently new
hydrazine and hydrazide derivatives or new combinations with other useful
ingredients have been disclosed in e.g. EP 0 254 195, U.S. Pat. No.
4,915,354, DE 3 629 078, EP 0 311 009, U.S. Pat. No. 4,816,373, U.S. Pat.
No. 4,686,167, EP 0 351 077, U.S. Pat. No. 4,833,064, U.S. Pat. No.
4,937,160, U.S. Pat. No. 4.912,016, U.S. Pat. No. 4,950,578, U.S. Pat. No.
4,975,354, U.S. Pat. No. 4,988,604. EP 0 399 460, U.S. Pat. No. 4,971,890,
U.S. Pat. No. 4,994,365, EP 0 420 005, EP 0 398 355, U.S. Pat. No.
4,971,888, U.S. Pat. No. 4,960,672, EP 0 393 711, EP 0 393 720, EP 0 393
721, and Japanese Unexamined Patent Publications 63-306438, 63-234245,
63-234244, 01-105941, 01-179982, 01-201650, 01-235943, 01-296238,
01-090439, 01-055549. These hydrazine and hydrazide compounds can likewise
be used in the present invention.
A second general class of suitable development nucleators consists of
reactive N-substituted cycloammonium quaternary salts corresponding to the
following general formula N-8:
##STR9##
wherein Q represents the necessary atoms to close an heterocyclic 5- or
6-membered ring or ring system, and R.sup.4 and Y can represent several
kinds of substituents depending on the specific chemical class. Useful
classes of N-substituted cycloammonium derivatives are disclosed in e.g.
U.S. Pat. No. 3,615,615, U.S. Pat. No. 3,759,901, U.S. Pat. No. 3,734,738,
U.S. Pat. No. 3,719,494, U.S. Pat. No. 4,115,122, U.S. Pat. No. 4,471,044
and Research Disclosure, Vol. 232, August 1983, Item 23213. Recent
disclosures on N-substituted cycloammonium derivatives include e.g.
Japanese Unexamined Patent Publications 01-61638, 01-217338, 01-217339,
01-20024 and 01-179142.
Other classes of suitable development nucleators are e.g.: sulphur
compounds e.g. thiourea dioxide, phosphonium salts e.g.
tetra(hydroxymethyl)phosphonium chloride, hydroxylamine,
bis-(p-aminoethyl)-sulphide and water-soluble salts thereof, reductic acid
and derivatives thereof e.g. 4,4,5,5-tetramethyl-reductic acid, kojic
acid, ascorbic acid, 2-hydroxy-1,3-cyclohexanedione,
2-acetoxy1,2-di(2-pyridyl)-ethanone, 2-hydroxy-1,2-di(2-pyridyl)-ethanone.
Mixtures of at least two of the above-mentioned development nucleators can
be used advantageously.
Prior to the coating of the composition that will form the photographic
layer comprising at least one development nucleator, the development
nucleator(s) can be dissolved in an organic solvent, e.g.
N-methyl-pyrrolidone, and added to said composition.
Alternatively the development nucleator(s) can be added in dispersed form
to the hydrophilic colloid composition that will form said emulsion layer.
In this case this dispersion can be prepared by dissolving these
nucleators first in at least one water-immiscible, oil-type solvent or
oil-former, adding the resulting solution to an aqueous phase containing a
hydrophilic colloid preferably gelatin and a dispersing agent, passing the
mixture through a homogenizing apparatus so that a dispersion of the oily
solution in an aqueous medium is formed, mixing the dispersion with a
hydrophilic colloid composition e.g. a gelatin silver halide emulsion, and
coating the resulting composition in the usual manner to produce a system
in which particles of development nucleator(s), surrounded by an oily
membrane, are distributed throughout the gel matrix. The dissolution of
the development nucleator(s) in the oil-former may be facilitated by the
use of an auxiliary low-boiling water-immiscible solvent. e.g.
ethylacetate, which is removed afterwards by evaporation.
The binder of the photographic element, especially when the binder used is
gelatin, can be hardened with appropriate hardening agents such as those
of the epoxide type, those of the ethylenimine type, those of the
vinylsulfone type e.g. 1,3-vinylsulphonyl-2-propanol, chromium salts e.g.
chromium acetate and chromium alum, aldehydes e.g. formaldehyde, glyoxal,
and glutaraldehyde, N-methylol compounds e.g. dimethylolurea and
methyloldimethylhydantoin, dioxan derivatives e.g. 2,3-dihydroxy-dioxan,
active vinyl compounds e.g. 1,3,5-triacryloyl-hexahydro-s-triazine, active
halogen compounds e.g. 2,4-dichloro-6-hydroxy-s-triazine, and
mucohalogenic acids e.g. mucochloric acid and mucophenoxychloric acid.
These hardeners can be used alone or in combination. The binders can also
be hardened with fast-reacting hardeners such as carbamoylpyridinium salts
as disclosed in U.S. Pat. No. 4,063,952.
The photographic element of the present invention may further comprise
various kinds of surface-active agents in the photographic emulsion layer
or in at least one other hydrophilic colloid layer. Suitable
surface-active agents include non-ionic agents such as saponins, alkylnne
oxides e.g. polyethylene glycol, polyethylene glycol/polypropylene clycol
condensation products, polyethylene glycol alkyl ethers or polyethylene
glycol alkylaryl ethers, polyethylene glycol esters, polyethylene glycol
sorbitan esters, polyalkylene glycol alkylamines or alkylamides,
silicone-polyethylene oxide adducts, glycidol derivatives, fatty acid
esters of polyhydric alcohols and alkyl esters of saccharides; anionic
agents comprising an acid group such as a carboxy, sulpho, phospho,
sulphuric or phosphoric ester group; ampholytic agents such as aminoacids,
aminoalkyl sulphonic acids, aminoalkyl sulphates or phosphates, alkyl
betaines, and amine-N-oxides; and cationic agents such as alkylamine
salts, aliphatic, aromatic, or heterocyclic quaternary ammonium salts,
aliphatic or heterocyclic ring-containing phosphonium or sulphonium salts.
Such surface-active agents can be used for various purposes e.g. as
coating aids, as compounds preventing electric charges, as compounds
improving slidability, as compounds facilitating dispersive
emulsification, as compounds preventing or reducing adhesion. Preferred
surface-active agents are compounds containing perfluorinated alkyl
groups.
The photographic element of the present invention may further comprise
various other additives such as e.g. compounds improving the dimensional
stability of the photographic element, antistatic agents, spacing agents,
light absorbing dyes. e.g. antihalation dyes, filter dyes or acutance
dyes, lubricants, opacifying compounds, e.g. titanium dioxide, and
plasticizers.
Antistatic agents can be used in one or more of the layers on the emulsion
side or in a backing layer.
Suitable additives for improving the dimensional stability of the
photographic element are e.g. dispersions of a water-insoluble or hardly
soluble synthetic polymer e.g. polymers of alkyl(meth)acrylates,
alkoxy(meth)acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl
esters, acrylonitriles, olefins, and styrenes, or copolymers of the above
with acrylic acids, methacrylic acids, Alpha-Beta-unsaturated dicarboxylic
acids, hydroxyalkyl (meth)acrylates, sulphoalkyl (meth)acrylates, and
styrene sulphonic acids.
Spacing agents can be present of which, in general, the average particle
size is comprised between 0.2 and 10 micron. Suitable spacing agents can
be made e.g. of polymethyl methacrylate, of copolymers of acrylic acid and
methyl methacrylate, and of hydroxypropylmethyl cellulose
hexahydrophthalate. Other suitable spacing agents have been described in
U.S. Pat. No. 4,614,708. Spacing agents can also serve as matting agents.
Other common matting agents consist of silica particles of which different
size classes can be used.
In the direct positive material of the present invention non-light
sensitive hydrophilic colloid layers can be present, e.g. a protective
layer and one or more backing layers. As stated above no undercoat layer
is needed since the masked stabilizers are incorporated in the emulsion
layers.
The support of the photographic material may be opaque or transparent, e.g.
a paper support or resin support. When a paper support is used preference
is given to one coated at one or both sides with an Alpha-olefin polymer,
e.g. a polyethylene layer which optionally contains an anti-halation dye
or pigment. It is also possible to use an organic resin support e.g.
cellulose nitrate film, cellulose acetate film, polyvinyl acetal film,
polystyrene film, polyethylene terephthalate film, polycarbonate film,
polyvinylchloride film or poly-Alpha-olefin films such as polyethylene or
polypropylene film. The thickness of such organic resin film is preferably
comprised between 0.07 and 0.35 mm. These organic resin supports are
preferably coated with a subbing layer which can contain water insoluble
particles such as silica or titanium dioxide.
The photographic direct positive materials of the present invention can be
exposed in any convenient way according to their particular application,
e.g. by daylight or by artificial light like tungsten light, xenon,
metal-halogen lamps, quartz-halogen lamps, by laser sources or invisible
radiation like ultraviolet, X-rays and infrared.
The processing of the photographic materials of the present invention
proceeds in a surface developer composed according to specifications
dependent on the particular use of the material.
The developing solution preferably contains one or more developing agents,
sulphite ions, bromide ions and polyalkyleneoxides. Preferred developing
agents are e.g. hydroquinone and derivatives. 3-pyrazolidinone derivatives
like 1-phenyl-5-pyrazolidinone ("Phenidone") and analogues, aminophenols,
hydroxylamin, hydrazine derivatives, and ascorbic acid and analogues.
Other adjuvants well known to those skilled in the art may be added to the
developer liquid of the present invention. A survey of conventional
developer addenda is given by Grant Haist in "Modern Photographic
Processing"--John Wiley and Sons--New York (1979) 220-224. Examples of
such addenda include complexing agents for calcium and magnesium ions,
present in hard water, e.g. ethylene diamine tetraacetic acid and
analogues compounds. Further can be present anti-foaming agents,
surface-active agents, biocedes, thickening agents like polystyrene
sulphonate and antioxidants like benzoate and cyclodextrine. The
developing liquid can contain so-called anti-sludge agents in order to
reduce dirt streaks on developed photographic material. The alkaline pH
value of the developing solution is preferably established by means of
conventional buffering agents like phosphate buffers, carbonate buffers
and borax buffers. The pH can be additionally adjusted to the desired
value by means of an alkali hydroxide, e.g. sodium or potassium hydroxide.
Finally the solution can contain hardening agents including latent
hardeners.
For processing preferably an automatically operating apparatus is used
provided with a system for automatic replenishment of the processing
solutions.
The development step can be followed by a washing step, a fixing solution
and another washing or stabilization step. Finally the photographic
material is dried.
The photographic direct positive materials of the present invention can be
used in various types of photographic elements such as e.g. in
photographic elements for graphic arts, for general amateur and
professional photography, for cinematographic recording and duplicating,
for radiographic recording and duplicating purposes, and in diffusion
transfer reversal photographic elements. A preferred application however
is micrographic recording, e.g. in a microfilm for computer output.
The following examples illustrate the invention without however limiting it
thereto.
EXAMPLES
Example 1
An octahedral silver bromide core-shell emulsion showing a final average
grain size of 0.3 micron was prepared by simultaneous addition of
equimolar solutions of silver nitrate and potassium bromide to a stirred
aqueous gelatin solution. The precipitation of the core was carried out at
70.degree. C. starting at a pAg of 6.80. After addition of 15% of the
total silver the pAg was changed to 8.71 and the precipitation was
continued until 50% of the total silver was consumed and an average core
diameter of 0.23 micron was reached. After bringing the gelatin/silver
ratio to 0.5 by dissolving 1 5 extra gelatin, this core was chemically
sensitized by means op 25.8.times.10.sup.-3 mmole of sodium thiosulphate,
16.3.times.10.sup.-3 mmole of chloroauric acid and 27.5.times.10.sup.-3
mmole of p-toluenethiosulphonic acid sodium salt, all expressed per mole
of silver halide. A shell was precipitated on this core at a temperature
of 50.degree. C. and a pAg of 9.4 7. After completion of the precipitation
the gelatin/silver ratio was again adjusted to 0.5 and the core-shell
emulsion was chemically ripened using 13.8.times.10.sup.-3 mmole of sodium
thiosulphate, 2.48.times.10 .sup.-3 mmole of aurochloric acid and
26.8.times.10.sup.-3 mmole of ammonium thiocyanate, all expressed per mole
of silver halide.
The finished emulsion was divided in aliquot samples and to each sample
were added 1.65 mmole/mole of AgNO.sub.3 of spectral sensitizing dye SD-1,
6.6 mmole/mole of AgNO.sub.3 of nucleating agent phenylformylhydrazide.
Finally various amounts of free benzotriazole (S-1), masked benzotriazole
(MS-1), free 5-methylbenzotriazole (S-2) and masked methylbenzotriazole (a
mixture of MS-2 and MS-3) were added as indicated in Table 2. Each
emulsion sample was coated on a transparent support at a coverage of 4.0
Ag/m.sup.2 expressed as AgNO.sub.3. Then the coatings were exposed through
a continuous wedge on a EG&G sensitometer using a 10.sup.-5 s flashlight
and developed at 35.degree. C. in a developer of following composition:
______________________________________
N-methyl-p-aminophenol 15 g
sodium sulphite anh. 110 g
sodium hydroxide 19 g
sodium carbonate 40 g
sodium bromide 3 g
hydroquinone 40 g
2-methylaminoethanol 40 ml
water to make 1 l
______________________________________
After development the coatings were treated in a conventional fixing bath
and finally washed and dried. The direct positive sensitometric
characteristics were evaluated and represented in Table 2a.
A second set of the same coatings was subjected to a treatment of 3 days at
57.degree. C.--34% relative humidity in order to simulate aging
properties. Then this second set was exposed, processed and evaluated as
the previous series. The results are represented in Table 2b.
TABLE 2A
__________________________________________________________________________
Sensitometry
coating No
Stabi.
Conc..sup.1
Dev .multidot. t .multidot. (s)
Dmin S.sup.2
Dmax Delta RR.sup.3
__________________________________________________________________________
1 S-1 10.sup.-3
30 0.10 1.60
2.2 1.10
2 MS-1 10.sup.-3
45 0.18 1.80
3.0 >1.2*
3 MS-1 10.sup.-2
45 0.11 1.55
2.8 >1.45*
4 S-2 10.sup.-3
30 0.09 1.50
2.4 1.05
5 S-2 10.sup.-2
60 0.08 1.35
2.6 1.20
6 MS-2/3
10.sup.-3
30 0.08 1.65
2.3 1.20
7 MS-2/3
10.sup.-2
45 0.06 1.35
2.4 >1.65*
__________________________________________________________________________
TABLE 2b
__________________________________________________________________________
Sensitometry 3 d 57.degree./34% RH
coating No
Stabi.
Conc..sup.1
Dev .multidot. t .multidot. (s)
Dmin S.sup.2
Dmax Delta RR.sup.3
__________________________________________________________________________
1 S-1 10.sup.-3
30 0.21 1.75
2.4 0.50
2 MS-1 10.sup.-3
45 0.37 1.70
3.2 0.85
3 MS-1 10.sup.-2
45 0.14 1.60
2.8 >1.4*
4 S-2 10.sup.-3
30 0.16 1.50
2.2 0.60
5 S-2 10.sup.-2
60 0.08 1.30
2.1 0.80
6 MS-2/3
10.sup.-3
30 0.18 1.65
2.6 0.90
7 MS-2/3
10.sup.-2
45 0.06 1.35
2.2 >1.65*
__________________________________________________________________________
Notes:
.sup.1 conc.: mole/mole AgNO.sub.3.sup.:
.sup.2 S: relative sensitivity expressed as relative log Et values, lower
figure means higher sensitivity;
.sup.3 Delta Rereversal = overexposure latitude measured between dir. pos
density 0.1 + Dmin and rereversal density 0.1 + Dmin;
*rereversa1 density is still below 0.1 + Dmin at highest exposure level.
Table 2 illustrates the better direct positive sensitometry and the more
extented overexposure latitude before encoutering rereversal when using
the masked stabilizers in comparison to the free stabilizers. The results
are most convincing with the mixture of compounds MS-2 and MS-3.
Example 2
A cubical silver bromide core-shell emulsion showing a final average grain
size of 0.3 micron was prepared by simultaneous addition of equimolar
solutions of silver nitrate and potassium bromide to a stirred aqueous
gelatin solution. The precipitation of the core was carried out at
60.degree. C. and at a pAg of 7.01. After addition of 50% of the total
silver the core grains were chemically sensitized by means of 25.
8.times.10.sup.-3 mmole of sodium thiosulphate, 16.3.times.10.sup.-3 mmole
of aurochloric acid and 27.5.times.10.sup.-3 mmole of p-toluenesulphonic
acid sodium salt, all expressed per mole of silver halide. Then the grains
were further grown under the same precipitation conditions until the final
average grain size was reached. The gelatin/silver ratio was brought to
0.5 by the addition of extra gelatin and the core-shell emulsion was
surface sensitized by means of 1.62.times.10.sup.-3 mmole of
p-toluenesulphonic acid sodium salt, 13.8.times.10.sup.-3 mmole of sodium
thiosulphate, 2.48.times.10.sup. -3 of aurochloric acid and
26.8.times.10.sup.- 3 of ammoniumthiocyanate, all expressed per mole of
silver halide.
The finished emulsion was divided in aliquot samples and to each sample
were added 2.0 mmole/mole of AgNO.sub.3 of spectral sensitizing dye SD-1
and 6.6 mmole/mole of AgNO.sub.3 of nucleating agent
phenylformylhydrazide. Finally various amounts of free
5-methylbenzotriazole (S-2) or masked methylbenzotriazole (a mixture of
MS-2 and MS-3) were added as indicated in Table 3. Each emulsion sample
was coated on a transparent support at a coverage of 4.0 Ag/m.sup.2
expressed as AgNO.sub.3. Then the coatings were exposed, developed during
different times, fixed, washed, dried and evaluated as in example 1. The
results are summarized in Table 3:
TABLE 3a
__________________________________________________________________________
Sensitometry
coating No
Stabi.
Conc..sup.1
Dev .multidot. t .multidot. (s)
Dmin
S.sup.2
Dmax
Delta RR.sup.3
__________________________________________________________________________
8 S-2 6 .times. 10.sup.-3
35 0.04
1.35
1.39
1.35
9 " " 45 0.08
1.50
1.93
0.90
10 " " 60 0.15
1.65
2.77
0.60
11 " 10.sup.-2
35 0.03
1.30
1.16
1.25
12 " " 45 0.05
1.35
1.32
1.05
13 " " 60 0.11
1.45
2.06
0.90
14 MS-2/3
6 .times. 10.sup.-3
35 0.05
1.50
2.22
>1.50*
15 " " 45 0.08
1.55
2.48
1.45
16 " " 60 0.14
1.60
3.27
0.60
17 " 10.sup.-2
35 0.04
1.50
1.95
>1.50*
18 " " 45 0.05
1.50
2.37
>1.50*
19 " " 60 0.07
1.50
2.80
>1.50*
__________________________________________________________________________
TABLE 3b
__________________________________________________________________________
Sensitometry 3 d 57.degree./34RH
coating No
Stabi.
Conc..sup.1
Dev .multidot. t .multidot. (s)
Dmin
S.sup.2
Dmax
Delta RR.sup.3
__________________________________________________________________________
8 S-2 6 .times. 10.sup.-3
35 0.06
1.50
1.78
1.25
9 " " 45 0.11
1.65
2.77
0.60
10 " " 60 0.53
1.65
3.09
0.40
11 " 10.sup.-2
35 0.04
1.35
1.40
1.25
12 " " 45 0.07
1.40
2.19
1.00
13 " " 60 0.16
1.20
2.22
0.90
14 MS-2/3
6 .times. 10.sup.-3
35 0.06
1.50
2.22
>1.50*
15 " " 45 0.09
1.60
2.85
>1.40*
16 " " 60 0.13
1.70
3.24
>1.30*
17 " 10.sup.-2
35 0.04
1.40
1.50
>1.60*
18 " " 45 0.05
1.50
1.92
>1.50*
19 " " 60 0.07
1.60
2.74
>1.40*
__________________________________________________________________________
Notes:
1, 2, 3: cfr example 1.
The results of Table 3 again illustrate the better direct positive
sensitometry and the more extended overexposure latitude before
encoutering rereversal when using the masked methylbenzotriazoles in
comparison to the free 5-methylbenzotriazole. Also the rereversal is
better impeded after simulation of aging.
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